Platform, adjustable in height

Abstract: A platform (1) is equipped with a chair (3), which chair is displaceable along a mast (2), and to which chair platform components (1-1,1-2) can be affixed, whereby, force indication means (9) are incorporated between the chair (3) and the platform components (1-1,1-2) so that an indication can be provided concerning the differences in the mechanical loading of the platform components located at opposite sides of the chair. A simple embodiment arises through the application of a beam (8) which is freely-spanned with respect to the chair (3) and which is connected in a hinged manner with the platform components (1-1,1-2), within which beam force indication means (9) are incorporated.

Description: The current invention pertains to a platform equipped with a chair, which chair is displaceable along a mast, to each side of which platform a platform component can be affixed, via two fixing points located above each other and embodied in a hinged manner, whereas a beam which is freely spanned with respect to the chair is fixed between the corresponding lowest hinged fixing points of the platform components and force indication means are fitted at least between one of the platform components and the chair. Such platforms, also referred to as scaffold-lifts, are generally known from NL-A-8603300. Known lift-scaffolds, scaffoldings and working platforms, which are mobile and which can be assembled in situ from modular sections or parts, are often placed adjacent to or against buildings or walls as an aid to building, repair or maintenance duties. Under such circumstances, a load with personnel is placed on the platform, which load and personnel are subsequently displaced on the platform alongside the mast. In operation of the known platforms circumstances are imaginable in which such forces exist that danger to material or persons cannot be ruled out. In order to mitigate said danger, the platform according to NL-A-8603300 is provided with indication means fitted at least between one of the platform components and the chair. The advantage thereof is that said force indication means provide an indication of the forces arising between the platform component and the chair, which, in their turn, exert a torque or bending force on the mast. The indication provides the possibility of warning when a mechanical overloading or imbalance occurs in the platform as a result of an excessive loading of one side of the mast, which overloading or imbalance could lead to dangerous situations. A disadvantage of the known platform resides in the fact that the force indication means due to their rather complicated and expensive embodiment do not garantee a precise and stable operation over extended periods of use. The aim of the present invention is to obviate the mentioned disadvantages and to provide a platform with simple and reliable force indication means. In order to achieve this, the platform according to the present invention is characterized in that the beam is equiped with a block with a boring within which boring a blocking pin protruding from the chair is fixed, whereas the force indication means are positioned between the block and a part fixed to the beam. In this manner a very reliable and inexpensive construction is obtained via which the relative movements of the chair and the beam are communicated to the force indication means. Due to the fact that the block is connected to the chair by a blocking pin, the block together with the indication means can be easily mounted within the beam itself. In that case a very good protection against atmospheric influences or damage from outside is obtained. A further embodiment of the platform according to the invention is characterised in that elastic means are provided between the block and the force indication means in order to pre-tense the force indication means. In a further embodiment the beam is equiped with striking means which limit the degree of movement of the beam with respect to the block. In this way overloading and consequent damage of the force indication means is avoided. Moreover, it is particularly preferable when the force indication means are embodied electronically to connect same to an affixation switch, so that a periodic feeling and checking of the correct working of the electronic force indication means can take place, so that a safe operation of the eccentric overload protection realized in this manner is guaranteed. Furthermore, it is preferable to control the protection circuit by means of a microprocessor, whereby the microprocessor is programmed in such a manner that disturbances in the further platform control system can be checked by means of a regular self-checking, and it is possible to take corrective actions in a timely manner and to return to a situation which is safer for the platform. It is to this end that the protection circuit on the displacement means for the chair contains connected releasing means, so that the platform can be released as soon as the overload situation no longer exists. The current invention and its further related advantages shall now be further elucidated on the basis of the attached figures, in which corresponding elements will be provided with the same reference numbers. The contents of the figures are as follows: Figure 1 shows a relevant portion of a possible embodiment of the platform according to the invention; and Figure 2 depicts a detail view of the arrangement of a beam which is to be used in the embodiment shown in figure 1. Figure 1 shows a depiction of a platform 1 which is composed of a mast 2, along which mast 2 a chair 3 can be adjusted in height with the aid of displacement means 4. The adjustment takes place with the aid of two motors 4-1 and 4-2, which motors cause one or more non-depicted cog-wheels to rotate, which cog wheels are connected to a pinion 5 affixed to the mast 2. In the partially-depicted embodiment, platform components 1-1 and 1-2 are affixed on opposite sides of the chair 3. Cover plates 6-1 and 6-2, respectively, are situated on the platform components 1-1 and 1-2, which platform components 1-1 and 1-2 are generally constructed downwards towards a point and are, for example, v-shaped, and which cover plates 6-1 and 6-2 serve as a loading floor. In the embodiment depicted here, the platform components 1-1 and 1-2 are affixed to the chair 3 by means of hinging fixing points 7-1 to 7-4, inclusive. Figure 1 shows that a beam 8 is fixed between the two undermost hinging fixing points 7-3 and 7-4, within which beam 8, force indication means 9 are fitted between the fixing points 7-3 and 7-4. These force indication means 9 are usually embodied electrically, with the aid of, for example, a piezo electric crystal, or on the basis of stretch-strips, in order to provide information in some manner concerning the magnitude and type of the force, that is to say a pulling or pushing force, which is being exerted. In the embodiment of the beam 8, the force indication means 9 are in integrated herein in such a manner that only a difference in pressure-force is measured, which difference is a result of a difference force, with which force, as a result of a possible difference between the loading occurring on the cover plates 6-1 and 6-2, or otherwise as a consequence of the non-symmetrical construction of the platform 1, the fixing points 7-3 and 7-4 are pushed towards each other. To this end, the beam 8 is equipped with a block 10, within which block 10 a boring 11 has been implemented. A blocking pin 12, which is fixed to the chair 3, is fixed within this boring 11. The beam 8 is freely-spanned with respect to the chair 3 and is capable of motion to some degree in its longitudinal axis. If the force on one of the fixing points 7-3 or 7-4 is greater than the force on the other fixing point 7-3 or 7-4, the blocking pin 12 on the block 10 moves somewhat, with the result hereof being that whenever the force in point 7-4 in the direction of the block is greater than the force in point 7-3 on the block 10, a pressing-force arises in the force indication means 9. In the opposite situation, a pulling-force is experienced in the means 9. This force is the result of a difference-force which arises in the respective platform components 1-1 and 1-2, which force in turn is a result of a difference, for example, between the weights of the loads which are placed on the cover plates 6-1 and 6-2 of the different platform components 1-1 and 1-2. By emitting an electric signal, the force indication means 9, which are usually electric, provide an indication regarding the platform component which is most heavily loaded, whereby, in this manner, information is also provided concerning the magnitude of the force which plays a role herein and which force is exerted in the mast 2 in the form of a torque or bending force. It should be clear that, based on the aforementioned given situation, variants are possible whereby, for example, in the connection route between the fixing point 7-3 and the chair 3, for example, force indication means 9 are incorporated, and also, whereby in a similar manner, force indication means 9 are incorporated in the connection route between the fixing point 7-4 and the chair 3. In that case, it is even possible that an insight is provided on a per- platform-component 1-1 and 1-2 basis into the magnitude of the previously mentioned bending force caused by each component. Figure 2 shows that elastic means 13 are incorporated in mechanical series with the force indication means 9, which elastic means 13 are preferably pre-tensed and which, by means of the exertion of force during the displacement of the blocking pin 12 and the block 10, can be brought under a pushing-force or otherwise under a pulling-force. The beam 8 is equipped with striking means 14 and 15 in order to ensure that, during the exertion of a pushing force on the force indication means 9, the force cannot reach a level whereby these means could be damaged by crushing. In a similar manner, the striking means 15 are incorporated to ensure that upon extension by pulling, the degree of freedom is restricted and that, in this pulling-force case, the force indication means 9 are not damaged by being overly pulled apart. The force indication means 9, which are preferably electronic in their embodiment, are connected to a non-depicted protection circuit, which protection circuit is arranged in such a manner that the means 9 are regularly scanned, in order to regularly check if the force indication means 9 and/or the electrical connections thereto are not short-circuited, and to check that the means 9 are no longer connected as a result of an open-circuit. In this manner, an extremely safe electric load indicator is created, which indicator functions correctly under all imaginable operational circumstances. If desired, the protection circuit, which is usually embodied with the help of a microprocessor, can also be coupled to further measures for the prevention of other undesirable occurrences, and is connected to non-depicted releasing means, in order to forbid the operation of the displacement means 4-1 and 4-2 under unsafe circumstances.

Claims: Platform equiped with a chair (3), which chair (3) is displaceable along a mast (2) to each side of which chair (3) a platform component (1-1, 1-2) can be affixed via two fixing points (7-2, 7-4; 7-1, 7-3) located above each other and embodied in a hinged manner, whereas a beam (8) which is freely-spanned with respect to the chair (3) is fixed between the corresponding lowest hinged fixing points (7-3, 7-4) for the platform components and force indication means (9) are fitted at least between one of the platform components and the chair, characterised in that the beam (8) is provided with a block (10), which is movable with respect to the beam, with a boring (11) within which boring a blocking pin (12) protruding from the chair (3) is fixed, whereas the force indication means (9) are positioned between the block (10) and a part fixed to the beam (8). Platform according to claim 1, characterised in that elastic means (13) are provided between the block (10) and the force indication means (9) in order to pre-tense the force indication means. Platform according to claims 1 or 2, characterised in that the beam (8) is equiped with striking means (14,15) which limit the degree of movement of the beam (8) with respect to the block (10).

Inventors: OCKHUIZEN JOHANNES BERNARDUS M, SMITS ANTONIUS HENRICUS JOHANN, VAN MOL JOHANNES CATHARINA FRA, OCKHUIZEN, JOHANNES BERNARDUS MARIA, SMITS, ANTONIUS HENRICUS JOHANNES, VAN MOL, JOHANNES CATHARINA FRANCISCUS
Applicants: HEK MANUFACTURING B V, HEK MANUFACTURING B.V.
Application year: 1994
Main classification: B66F11
IPC codes: B66F11, B66F17